Computing device



sepnzs; 1951 W. C. MORRISON COMPUTING DEVICE 4 Sheets-Sheet 2 Filed June5, 1946 l -WMW @mm L l Sept. 25, 1951 w. c. MORRISON con/IPUTINC; DEVICEim m ma An w h V Z .l s m d A .d m Y m W a s 4 .uw in. .nf Y mvo qmIllrr Q: Nvu

Snwmmw m S1 ww S. mkv n" 1 5. e i nog. 1m. .m .m mw nm Shaw-NW sept. z5,1951 Filed June 5, 1946 4 Sheets-Sheet 4 s A A 4 Y u' "f5 i \l. "n ff; bv L "Y A u BY iwf/Wsw e/LL Patented Sept. 25, 1951 2,568,927 COMPUTINGDEVICE Wendell C. Morrison, Princeton, N. J., assignor -to RadioCorporation of America, a corporation of Delaware Application June 5,1946, Serial No. 674,503

4 Claims. l

This invention relates to computing devices such as are adapted todetermine the characteristics of the resultant field pattern produced byan antenna. array at a point P which may be considered as moving aroundthe several antennas on the periphery of a circle having a radius verylarge as compared to the spacing between the antennas. 'I'he computingdevice of the present invention is in the nature of an improvement onthe computing device disclosed by George H. Brown in Patent 2,337,968.

As pointed out in the aforesaid patent. there are four variables of eachantenna of the array that are involved in the production of theresultant eld pattern at the point P. In the case of each antenna, thesevariables are (l) the current, (2) the phase, (3) the spacing withrespect to one of the other antennas which is called a reference antennaand is located on a reference line. and (4) the angular relation betweenthe reference line and a line joining the antenna under considerationwith the reference antenna. From these variables of the antennas of thearray may be computed the resultant field strength at any point P at anyangle p from the reference line on which the reference antenna islocated.

.Such resultant eld can be detected to provide a. unidirectionalpotential proportional in value to the strength or intensity of theresultant field. In accordance with the present invention, there isproduced a. detected voltage which (l) is mathematically equivalent tothe field from an antenna array, and (2)- is combined with alternatingpotentials which are in quadrature and are applied respectively to thehorizontal and vertical deilectors of a cathode ray oscillograph. As aresult, the cathode ray follows a generally circular path having aradius which varies in accordance with the value of the detected voltageso that there is traced on the fluorescent screen of the oscillograph apattern which'is representative of the resultant field produced by theantenna array and may be evaluated in terms of this iield.

Important objects of the invention are the provision of an improvedfield pattern computing device and method of operation for determiningthe eldpattern of the energy radiated from an antenna array, and theprovision of an improved means or controlling or guiding the movement ofthe cathode ray of an oscillograph or the like.

The invention will be better understood from Referring to the drawings:

Figure 1 is an explanatory diagram relating tothe operation of theimproved computing device of the present invention,

Figure 2 is a block diagram of this computing device,

Figure 3 is a wiring diagram of the device of Figure 2,

Figure 4 is a wiring diagram of the deflecting circuit of theoscilloscope, and

Figure 5 illustrates three sets of explanatory curves relating to aphase modulation feature of the invention similar to that disclosed byR. D. Kell in Patents 2,061,734 and 2,280,707.

Figure 1 is like Figure l of the aforesaid Patent 2,337,968 (250-33). Itshows (1) a first vertical antenna a which is located on a referenceline L, a second vertical antenna b which is 1ocated at a distance dasor from the antenna a and at an angle 9b from the reference line L. and(3) a vertical antenna c which is located at a distance d orfrom theantenna a and at an angle 0o from the reference line L. The problempresented for solution is the determination of the resultant fieldpattern produced by the antennas a, b, and c at any point P, which is atany angle e from the reference line L.

In solving this problem, the current of the antenna a. is taken as unityand is designated as Ia. The current Ib of the antenna b is equal to aquantity M at a phase angle ab. The current Ic of the antenna c is equalto a quantity N at a phase angle ac. The angle o of the point P withrespect to the reference line L may vary from 0 to 360 degrees.

A detailed explanation of how these various factors are involved in theproduction of the intensity of the resultant iield at the point Pis tobe found in the aforesaid patent and in an article entitled DirectionalAntennas by George H. Brown, published in the January 1937 issue of theProceedings of the Institute of Radio Engineers. In considering thepresent invention, certain mathematical equations and terms taken fromthese prior publications will be brought into this disclosure asoccasion demands. The various details of the computing device itselfwill be better understood from Figure 2.

As indicated by Figure 2, this computing device includes a plurality ofchannels A, B, C, etc., there being one channel for each antenna broughtinto the consideration of the pattern of the resultant field at thepoint P. With the exception of the channel A (representing the antenna awhich is located on the reference line L and has a current of unity),these channels are alike. The outputs of all the channels are combinedin a mixer I and the resultant output is detected by a detector II toproduce a unidirectional potential which (1) has at each instant a valueproportional to the intensiy or amplitude of the resultant field at thepoint P and (2) is combined with the deecting voltage of the circuit ofFigure 3 to control the path of the cathode ray on the fluorescentscreen of the oscillograph.

Thus the channel C, for example, includes (1) a low frequency source I2,(2) a phase shifter I3 which has a setting determined by the phase angle9c between the antenna c and the reference line L, (3) a variable levelclipper I4 which responds to the low frequency output of the phaseshifter I3 and to a 100 kc. saw-tooth frequency derived from anoscillator I5 through a saw-tooth generator I6 and a saw-toothlinearizing tube II, (4) a diiierentiator. clipper and 100 kc. amplifierI8, (5) a 300 kc. tripler I9, (6) a 900 kc. tripler 20, and (7) anamplifier 2I which is made to have a gain proportional to the value N ofthe current of the antenna c. The devices I4 and I8` function to provide(1) a fixed phase shift in the carrier proportional to the phase ac ofthe current N in the antenna c and (2) a phase modulation of the carrierproportional to the distance McIa sin wt=Ic sin wt and the fieldproduced at the point P due to both antenna a and antenna c is equal toIa sin wt -I- Ic sin [wt-l-ac-lcos (oct-9d] The output voltage of theamplifier 2Il is made proportional to Ic sin wt.

The channel B likewise (1) is connected to the low frequency source I2through a phase shifter 22, (2) is connected to the oscillator I5through the saw-tooth generator I6 and the saw-tooth linearizing tubeI1, and (3) includes a differentiator-clipper-amplier 23, a 300 kc.tripler 24, a 900 kc. tripler 25 and a variable gain amplifier 26 whichhas its output connected to the mixer I0. The output voltage of theamplifier 26 is proportional to MbIa sin wt=Ib sin wt.

The channel A includes the oscillator I5, a 300 kc. tripler. 21, a 900kc. tripler 28 and a 900 kc. amplifier 29 which has its output connectedto the mixer I0. The voltage E29 appearing at the output of the amplier29 is equal to 1.0 sin wt and is proportional to the intensity of thefield produced at the point P by the antenna a.

As previously indicated, the eld produced at the point p by two antennasa and b is equal to (2) Take from an oscillator of frequency fu avoltage en which can be shifted in phase through angle 0b (3) Use en tophase modulate e2 giving e2=kIb sin [ult-I- cos (wot-69] (4) Phase shiftez an amount ab giving 5): Add e1 and e2' giving The sum Ezl-l-Ezs-l-Ezgis a resultant voltage which is proportional to the resultant fieldintensity produced at the point P by the antenna a, b and c. If thefields of additional antennas, such as d, e, etc. require consideration,additional channels similar to the channels B and C are connected intothe circuit of the device as indicated by the legends of Figure 2.

In any case, the resultant voltage (Ezi-l-Eze-i-Eza etc.) is derived inthe mixer I0 and detected by the detector II which provides aunidirectional potential E11 having a value proportional to theintensity of the resultant field produced at the point P by the variousantennas taken into consideration.

This unidirectional voltage En is applied to the leads 30 and 3I of thecathode ray deecting circuit of Figure 3. Y

The deflecting circuit of Figure 3 includes a pair of identicalpush-pull amplifiers 32-33 and 34-35 which have potentials applied totheir anodes and screen grids from a|B terminal and have their cathodesgrounded. Ampliers 34-35 are connected to apply to the verticaldeiiectors 31 of a cathode ray oscillograph 38 an alternating potentialwhich is in quadrature with that applied to the horizontal deectors 39of this oscillograph by the amplifiers 32-33. The oscillograph 38 has afluorescent screen 40 at its enlarged end and is otherwise of aconventional type well known to those skilled in the art. It is wellknown that the application of quadrature potentials to the vertical andhorizontal deflectors of such an oscillograph causes the cathode ray totrace a circular path on the screen 40. As hereinafter explained, thispath is made to have a very short radius in the absence of the potentialEn and is made to increase in radius as the value of En increases sothat there is produced on the screen 40 a pattern which isrepresentative of the field intensity at the point P and is repeatedonce for every cycle of the defiecting potential.

It will be noted that the tubes 32, 33, 34 and 35- are of the pentagridconverter or heptode type which includes a cathode 4I, a first controlgrid 42, a screen or shield grid 43, a second control grid 44 which isshielded from the other electrodes of the heptode by the screen grid 43,and a suppressor grid 45 which functions to drive secondary electronsback to an anode 48. The voltage En is applied to the second controlgrids of all the heptodes 32 to 35 in parallel through a circuit whichincludes a bias control resistor Ri, a resistor Rz, a lead 41 and theground connections.

Low frequency alternating potential is applied to the second controlgrids of the heptodes 32 to 35 from a push-pull phase shifter 48 whichincludes a transformer 49 and a delay network 58. Thus the push-pullpotentials of the second control grids of the devices 32 and 33 arederived from one end of the network 50 through the resistors 5I and 52,and the push-pull potentials of the second control grids are derivedfrom the other end of the network 50 through the resistors 53 and 54.The characteristics of the network 50 are made such that alternatingpotentials applied to the second control grids of the heptodes 32 and 33are in quadrature with those applied to the second control grids of theheptodes 34 and 35 as indicated by the legends applied to the leads ofthe different second control grids.

Since the low frequency potential is applied in push-pull, theunidirectional voltage En is applied in parallel, and the output of theamplifiers 32-33 and 34-35 is taken oi in push-pull, none of the inputsignal E11 will appear in the output. This might suggest a similarity tothe balanced modulators used in suppressed carrier transmission work.There are distinctions, however, which should be recognized. In thecircuit of Figure 3, (1) the signal that would be the carrier in abalanced modulator is a unidirectional potential of variable amplitude,(2) the amplifiers are operated near cut-off grid bias potential, and

(3) the push-pull signal that would be a varying voice signal in abalanced modulator is fixed. As a result, the output of the amplifiers32--33 and 34--35 does not consist of the side bands of the lowfrequency with the voltage Eu suppressed but does consist of a lowfrequency potential with an amplitude which varies in accordance withthe value of the voltage En.

Figure 4 shows the connections of the various elements represented inFigure 2 as boxes, the same reference numerals being applied tocorrespending parts of the two figures. Most of these parts are ofconventional design and readily understood without detailed explanation.As an aid in practicing the invention, suitable values for onemodification are placed adjacent the various parts in units which arerecognized by those skilled in the art, and n cases of possibleambiguity the units have been indicated. They are not to be taken ascritical for the reason that diierent sets of values will be applicableto different uses of the invention.

The 100 kc. oscillator I5 includes the anode 56. the cathode 51, thegrid 58, the crystal 58 and the LC circuit 60 which is tuned to 100 kc.The output of this oscillator is coupled through a capacitor 6I to thegrid 62 of the saw-tooth discharge triode 63-62-64 and to thegrid 55 ofa triode 66-65-61 The triode 55-65-61 functions, together with a triode58-69-10 and the output network of the triode 68-69-10. to produce at anoutput lead 1I a sinusoidal `potential -of 300 kc. The tripler 21 formedby the triodes 66-65-61 and 58-69--10 and the output circuit of thelatter triode is fundamentally a symmetrical clipper with a tunedcircuit in its output. The square wave which it produces is very rich inodd harmonies so that the output is readily tuned to select the desiredharmonic.

anche? This harmonic is delivered through' the lead 1I to the tripler 28which is similar to the tripler 21, and the 900 kc. output is amplied bythe amplifier 29 and applied to the mixer tube I0 as previouslyexplained in connection with Figure 2.

The output of the saw-tooth discharge triode is connected through a.lead 12 to the grid of saw-tooth linearizing tube I1 and through a lead14 to the grid 15 of a selective diterentiator 16.

The selective diflerentiator 16 includes the triode 11, 15, 18 whichresponds only to negative changes in the potential applied to the grid'I5 through the lead 14 and a capacitor 19, and delivers at its outputlead a pulse for producing a synchronized saw-tooth wave for thechannels D and E which are similar to the channels B and C and deliverstheir outputs to the mixer I0 as previously indicated.

The saw-tooth linearizing triode 8I-13-82 functions to make thesaw-tooth wave more linear because of the compensating curvature of itscharacteristic, and delivers its output (1) through leads 83 and 84 anda `capacitor 85 to a coupling network interposed between the phaseshifter I3 and the variable level clipper I4 of the channel C, and (2)through the lead 83, a lead 86 and a capacitor 81 to a similar networkinterposed between the phase shifter 22 and the variable level clipper55 of the channel B.

The phase shifter I3 of channel C includes three conventional constantamplitude RC phase Shifters 88. 89 and 90 which are connected in cascadeand have their control elements ganged Y together as indicated by thedotted line 9| so as to provide a phase shift of' 360 degrees. Thecontrol element 9| is adjusted to produce a phase shift proportional tothe angle @c between the reference line L and the antenna c aspreviously explained. The output of the phase shifter I3 is deliveredthrough a capacitor 82 to a low frequency resonant circuit 93-94 inshunt with which there are connected a resistor 95, a trimmer resistor96 and a resistor 81 which is provided with a sliding contact 98 foradjusting the low frequency output to an amplitude proportional to thespacing between the antenna c and the reference line L.

The saw-tooth carrier is applied to the variable level clipper I4through lead 84 and capaci- 'tors 85 and |00. The gate of this clipperI4 has its level or position controlled by two voltages. The rst ofthese voltages is a unidirectional one which (1) is derived from aresistor |02 through a movable contact |03 and resistors |04 and 105 and(2) is made proportional to the phase angle ac of the current N of theantenna c. The second of vthese voltages is a sinusoidal or alternatingvoltage which (1) is derived from the resistor 91 and (2y moves the gateof the clipper up and down continuously at the low frequency rate of thesource I2. A

The variable level clipper I4 functions to clip the positive andnegative peaks of the saw-tooth carrier and to deliver to theclipper-amplierdifferentiator stage I8 a carrier wave of trapezoidalform. The form of the original carrier is illustrated in Figure 5 atI-A, lI-A and III-A. At I-B, II-B and lII-B is shown the clipping effectat one side of the gate for diierent values of the unidirectionalpotential applied to it. At I-C, II-C and III-C is shown the clippingeffect at the other side of the gate. The result of these two clippingeffects is the trapezoidal wave shown at I-D, lI-D and III-D. It will benoted that the length of the trapezoidal wave is diierent in each ofthese three cases.

The variable level clipper |4 includes a triode |`||0||08, a triode|09-l |0| which has a resistor I2 in its anode lead and a resistor ||3common to the cathodes |08 and This 'clipper delivers to the triode |5|a Wave of the type shown in Figure 5 at I-D, II-D and III-D.

The triode |I6| |5| functions to amplify this trapezoidal wave and tosquare off its positive half cycles due to its operation without fixedbiased potential.

From the triode ||6| |5| I1, the trapezoidal wave is applied to thedifferentiator ||9|2|| which produces at the grid |22 of the triode|2||22|23 a wave of the type shown in Figgure 5 at I-E, II-E and III-E.The grid |22 is biased through a resistor |32 to a potential such thatthis differentiated wave is clipped to the form shown in Figure 5 atI-F, II-F and III-F. This differentiated and clipped wave is utilized toshock excite a circuit |24 which is tuned to a frequency of 110 kc. Theresulting 100 kc. output is applied to the tripler I9 which delivers itsoutput to the tripler 20 as indicated in connetcion with the triplers 2land 29 of channel A.

The 9'00 kc. output of the tripler 20 is applied to the control grid |25of the variable gain amplifler 2|. Also applied to this grid is a biasvoltage which is varied so as to make the output voltage of the amplier2| proportional to the current N of the antenna C.

This bias voltage is derived from a -75 v. lead through resistors |25.|26 and |21, a sliding contact |28 and a switch |29. The relationbetween the switch |29 and the contact |28 is such that, when thecontact |28 approaches the end of its travel in the counter-clockwisedirection, the switch |29 snaps to its left hand closed position thusmaking the grid |25 almost '75 volts negative, reducing the gain of theamplier to zero, and eliminating the channel c as a factor in the nalresult.

The output voltage E21 of the amplier 2| thus has an amplitude and phasedetermined by (1) a component dependent on the adjustment of the lowfrequency phase control member 9|, (2) a component dependent on theadjustment of the gate by means of the slider 98, (3) a componentdependent on the adjustment of the gate by means of the slider |03, and(4) a component dependent on the adjustment of the slider |21 by whichthe bias potential of the grid |25 is determined.

This voltage E21, together with similar voltages derived from thechannels A, B, D, etc. is applied to the control grid |35 of the mixertube I0.

Thus the invention is characterized by (1)*a plurality of similarchannels in each of which is originated such factors as are required tomeet the mathematical requirements for determining the intensity of thefield produced at a given point by a different antenna, (2) by means forderiving a resultant potential having a value which varies in proportionto the resultant field produced at the given point by all thediierentantennas and (3) by an improved cathode ray oscillograph deilectingcircuit whereby deflecting voltages in quadrature are made to vary inamplitude in accordance with a single unidirectional potential.

The instantaneous amplitude of the output of I0 is proportional to theinstantaneous field at point P with one cycle of the low frequencymodulating voltage corresponding to one revolution of the point P aroundthe array.

The envelope of this voltage-obtained from the detector ||is aunidirectional Voltage which varies proportional to the eld intensity atpoint P. Again one cycle of the low frequency modulating voltagecorresponds to a 360 degree rota-v tion of point P around the array.

The output from the detector can be used directly to give a rectangularcoordinate plot. The horizontal saw-tooth sweep on the oscilloscope isoperated at a rate synchronous with the low frequency modulating voltageand the output of the detector is applied to the vertical deectionplates of the oscilloscope. 'I'hen one horizontal sweep corresponds tothe 360 around the antennas and the vertical deflection is proportionalto the eld intensity at each particular angle.

I claim as my invention:

L '.Ihe combination of a cathode ray ldevice having vertical andhorizontal deflectors, means for applying to said deflectors potentialswhich are in quadrature, means for varying said potentials by a singleunidirectional potential whereby the radius of the path followed by theray of said device is determined, means lfor producing an eiectproportional to the intensity of the field produced at a given point bya radiation source spaced from said point, and means responsive to saideect for varying the value of said unidirectional potential.

2. The combination of a cathode ray device having vertical andhorizontal deflectors, means for applying to said deilectors potentialswhich are in quadrature, means for varying said potentials by a singleunidirectional potential whereby the radius of the path followed by theray of said device is determined, means for producing an effectproportional to the intensity of the resultant field produced at a givenpoint by different radiating sources spaced from said point and from oneanother, and means responjsive to said effect for varying the value ofsaid 5 ;4\, unidirectional potential.

3. The combination of a cathode ray device having vertical andhorizontal deflectors, a pair of push-pull ampliers each having anoutput circuit connected to a different one of said deflectors and eachincluding a pair of electron discharge devices each having a pair ofcontrol grids, means for applying a rst unidirectional potential to onegrid of each of said devices in parallel, means for applying to theother grids of said devices push-pull potentials which are out of phasewith one another, a clipper including an input circuit and an outputcircuit, means for applying a second unidirectional potential to saidinput circuit, means for applying to said input circuit a carrier wavewhich is limited in accordance with a low frequency potential of apredetermined phase, means for differentiating the output wave of saidclipper, means for clipping said differentiated wave, a tuned circuitarranged to be shock excited by said diil'erentiated and clipped wave,means including a third amplifier having an input circuit responsive tothe output of said tuned circuit, means for applying to said thirdamplifier input circuit a potential having components corresponding tothe azimuth, the spacing and the phase of the current of a givenradiator with respect to a reference condition and additional means forvarying the amplitude of the output potential of said third amplier, andmeans in- .manuuu put of said third amplifier.

4. The combination of a cathode ray device Y having vertical andhorizontal deflectors, a pair of push-pull amplifiers, each having anoutput circuit connected to a diierent one of said deectors and eachincluding a pair of electron discharge devices each having a pair ofcontrol grids, means for applying a unidirectional potential to one gridof each of said devices in parallel. means for applying to the othergrids of said devices push-pull potentials which are out of phase withone another, means for producing an effect proportional to the intensityof the resultant field produced at a given point by different radiatingsources spaced from said point and from one another, and meansresponsive to said effect for varying the value of said unidirectionalpotential.

WENDELL C. MORRISON.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date A 2,153,638 Norman Apr. 11, 19392,213,172v Sherman Aug. 27, 1940 2,233,275 Wolff Feb. 25, 1941'2,248,852 Cannon July 8, 1941 2,265,848 Lewis Dec. 9, 1941 2,273,511Bruck Feb. 17, 1942 2,312,761 Hershberger Mar. 2, 1943 2,337,968 BrownDec. 23, 1943 2,391,862 Boyle Jan. 1, 1946 2,419,550 Hardy Apr. 29, 19472,421,312 Bobb May 27, 1947 2,425,999 Crosby Aug. 19, 1947 2,432,944Shillington Dec. 16, 1947 2,442,770 Kenyon June 8, 1948 2,457,580 MayerDec. 28, 1948

